You cannot use the Hardware PWM modules to generate a 50Hz PWM signal. Use your timer instead to interrupt at every 10ms for every half cycle. In the ISR decide which channel to fire. Use another variable (0-to-10ms) timebase to shut the firing output. You thus get the PWM @ 50Hz. What is choice of development ? ASM, C, Basic ???? I may find some time to post some sample codes.